Improve search in array

Question

I'm a newbie to Android and Java so please be nice :)

I have an EditText in my application which is used to search for a particular string in a String[]

My code works well, but not as I want:

ArrayList<String> allProd = new ArrayList<String>;
ArrayList<String> allProd_sort = new ArrayList<String>;

allProd = [the table is brown, the cat is red, the dog is white];

String[] allProdString = allProd.toArray(new String[allProd.size()]);

...

 //inputSearch is the EditText
 inputSearch.addTextChangeListener (new TextWatcher() {

   ...

   @Override
   public void onTextChanged(CharSequence charSequence, int i, int i2, int i3) { 

     int textLength = inputSearch.getText().length();
     String text = inputSearch.getText().toString();

     for (int y = 0; y< allProdString.length; y++) {

        //in my case i want that the search start when there are min 3 characters in inputSearch
        if(textLength <= allProdString[y].length() && textLength >=3) {

           if (Pattern.compile(Pattern.quote(text), Pattern.CASE_INSENSITIVE)
                                .matcher(allProdString[y]).find()) {

               allProd_sort.add(allProdString[y]);

           }

        }
     }

   }

 });

This code produces these results:

if I search for "table is" => allProd_sort will be [the table is brown]

but if I search for "table brown" => allProd_sort will be empty but I want [the table is brown]

how can I improve this?

thanks everybody

Answer 1

You need to change the pattern. At the moment the string needs to contain exactly what you entered. If instead of the space you put "table.*brown" it would match.

You can either have the user enter the regex, or you can do a simplified thing yourself by replacing all whitespace in the query string with ".*" before using it to match on.

You can read all about regular expressions here: http://docs.oracle.com/javase/tutorial/essential/regex/

Answer 2

Ok - first optimization: Only enter the loop, if your initial requirement (Searchtext >=3) is true:

@Override
public void onTextChanged(CharSequence charSequence, int i, int i2, int i3) {

  int textLength = inputSearch.getText().length();

  if (textLength < 3) return;

  String[] searchPattern = inputSearch.getText().toString().toLowerCase().split("\\s+");

  for (int y = 0; y< allProdString.length; y++) {

    if(textLength <= allProdString[y].length()) {
       if (matchSearch(allProdString[y].toLowerCase(), searchPattern)) {

           allProd_sort.add(allProdString[y]);

       }

    }
 }

If you only want to match lines, where all words are contained in the same sequence you can simply create a regular Expression like Tim B said.

But if you also want to match strings which contain the words anywhere search search "brown table" -> [the table is brown] then you need a little loop:

public boolean matchSearch(String s, String[] searches) {
    for (String search : searches) {
        if (!s.contains(search) return false; // If the word is not in the string FALSE
    }
    return true; // If all words were found in the string, it is a match!
}

---

To make this a bit clearer -> brown.*table will only match Strings where table comes after brown... I don't think you can easily create an efficient RegEx to check if each word is at least one time anywhere in the string...